Method for preparing coated abrasive having three-dimensional abrasive structures

Abstract

The method of the subject invention, which comprises (a) forming a plurality of abrasive structures having a three-dimensional shape on a backing by using a first abrasive slurry and drying the abrasive structures, and (b) spray-coating in a specific way a second abrasive slurry over the three-dimensional abrasive structures to form a coating layer and drying the coating layer, provides a coated abrasive having improved flexibility, surface roughness, and use life.

1. A method for preparing a coated abrasive having three-dimensional abrasive structures, comprising:
 (a) forming a plurality of abrasive structures having a three-dimensional shape on a backing by using a first abrasive slurry and drying the abrasive structures, and 
 (b) spray-coating a second abrasive slurry over the three-dimensional abrasive structures to form a coating layer thereon and drying the coating layer, 
 wherein the second abrasive slurry is sprayed over the abrasive structures at an angle (A) calculated by formula I:
     A =atan { H /( D−R/ 2)}  (I)
 
 
 
       in which A is the angle between the line of spray and the horizontal line, H and R are the height (μm) and the diameter (μm) of the three-dimensional abrasive structure, respectively, and D is the distance (μm) between two adjacent three-dimensional abrasive structures. 
     
     
       2. The method for preparing a coated abrasive of  claim 1 , wherein the first abrasive slurry comprises 40 to 70% by weight of abrasive grains, 20 to 50% by weight of an adhesive and 2 to 30% by weight of a filler based on the total weight of a solid content of the slurry. 
     
     
       3. The method for preparing a coated abrasive of  claim 1 , wherein the first abrasive slurry used in step (a) has a viscosity of 25,000 to 60,000 centipoise (at 25° C.) and a solid content of 80 to 95% by weight. 
     
     
       4. The method for preparing a coated abrasive of  claim 1 , wherein the first abrasive slurry in step (a) is coated in an amount of 100 to 1,000 g/m 2  on the backing. 
     
     
       5. The method for preparing a coated abrasive of  claim 1 , wherein the three-dimensional abrasive structures formed in step (a) has a diameter of 300 to 2,500 μm and a height of 300 to 1,000 μm, and the distance between the structures is 500 to 3,000 μm. 
     
     
       6. The method for preparing a coated abrasive of  claim 1 , wherein the three-dimensional abrasive structures formed in step (a) has a shape of cone, semicircle, cylinder or square pillar. 
     
     
       7. The method for preparing a coated abrasive of  claim 1 , wherein the first abrasive slurry in step (a) is coated by using a screen mesh roll coater. 
     
     
       8. The method for preparing a coated abrasive of  claim 7 , wherein the hole size of the screen mesh roll coater is 300 to 2,000 μm in diameter. 
     
     
       9. The method for preparing a coated abrasive of  claim 1 , wherein A is in the range of 10 to 70°. 
     
     
       10. The method for preparing a coated abrasive of  claim 1 , wherein the spray-coating is carried out using at least one injection nozzle located at a position above the three-dimensional abrasive structures formed on the backing. 
     
     
       11. The method for preparing a coated abrasive of  claim 1 , wherein the second abrasive slurry used in step (b) has a viscosity of 1,000 to 3,000 centipoise (25° C.) and a solid content of 60 to 80% by weight. 
     
     
       12. The method for preparing a coated abrasive of  claim 1 , wherein the second abrasive slurry is coated in an amount of 500 to 1,200 g/m 2  on the three-dimensional abrasive structures. 
     
     
       13. The method for preparing a coated abrasive of  claim 1 , wherein the three-dimensional abrasive structures formed in step (b) have an average height of 300 to 1,000 μm. 
     
     
       14. A method for preparing a coated abrasive having three-dimensional abrasive structures, comprising:
 (a) forming a plurality of abrasive structures having a three-dimensional shape on a backing by using a first abrasive slurry and drying the abrasive structures, 
 (b) spray-coating a first abrasive composition over the three-dimensional abrasive structures, electrostatic-coating abrasive grains, followed by drying, to form a first adhesive layer, wherein the first adhesive composition is sprayed over the abrasive structures with an angle (A) calculated by the formula I:
     A =atan { H /( D−R/ 2)}  (I)
 
 
 (c) spray-coating a second adhesive composition over the first adhesive layer, followed by drying to form a second adhesive layer, in which the second adhesive composition is sprayed over the first adhesive layer at an angle (A′) calculated by the formula II:
     A ′atan { H′ /( D−R/ 2)}  (II)
 
 
 
       in which A or A′ is the angle between the line of spray and the horizontal line, H and R are the height (μm) and the diameter (μm) of the three-dimensional abrasive structure, respectively, H′ is the height of the three-dimensional abrasive structures obtained in (b), and D is the distance (μm) between two adjacent three-dimensional abrasive structures. 
     
     
       15. The method for preparing a coated abrasive of  claim 14 , wherein the first adhesive composition used in step (b) has a viscosity of 1,000 to 2,000 centipoise (25° C.) and a solid content of 70 to 80% by weight, which is coated in an amount of 70 to 250 g/m 2 . 
     
     
       16. The method for preparing a coated abrasive of  claim 14 , wherein the 30 second adhesive composition used in step (c) has a viscosity of 500 to 2,000 centipoise (25° C.) and a solid content of 60 to 80% by weight, which is coated in an amount of 50 to 300 g/m 2 . 
     
     
       17. The method for preparing a coated abrasive of  claim 14 , wherein the amount of abrasive grain used in step (b) is coated in the range of 100 to 600 g/m 2 . 
     
     
       18. The method for preparing a coated abrasive of  claim 14 , wherein the first abrasive slurry used in step (a) has a viscosity of 25,000 to 60,000 centipoise (at 25° C.) and a solid content of 80 to 95% by weight. 
     
     
       19. The method for preparing a coated abrasive of  claim 14 , wherein R is 300 to 2,500 μm, H is 300 to 1,000 μm, and D is 500 to 3,000 μm. 
     
     
       20. The method for preparing a coated abrasive of  claim 14 , wherein A is in the range of 10 to 70°.